Star Trek: Picard season 3: everything you need to know about the show's Big Bad

(Image credit: Paramount+)

Spoilers for Picard season 3's third episode follow. If you haven't seen the latest episode or caught up on the season so far, look away now!

Following on from the bombshell that Jean-Luc Picard and Beverly Crusher have a kid together, the big revelations keep on coming in Star Trek: Picard season 3. Third episode ‘Seventeen Seconds’ has just confirmed the identity of the villains who used a stolen portal weapon to destroy a Starfleet recruitment facility on M’talas Prime, and it turns out we’ve met them before.

The shapeshifting Changelings were the principal aggressors in Star Trek: Deep Space Nine, and now they’ve returned to the Alpha Quadrant with new-and-improved CG morphing techniques. Aside from stealing top-secret Starfleet hardware, their ultimate goal remains unknown, though whatever they have planned is unlikely to be good news for Jean-Luc and the Federation.

So, as one Changeling spy gets busy creating havoc on the USS Titan, and another winds up interrogated (and vaporised) by Worf and Raffi Musiker, we travel back in time to explore the Dominion’s Star Trek origins.

Where have we seen the Changelings before in Star Trek?

The shapeshifting Changelings became the main antagonists of Star Trek: Deep Space Nine, which ran for seven seasons from 1993-99. DS9 security chief Odo was a member of the same species, though he didn’t learn about his heritage until season 3.

The Changelings originated on the other side of the galaxy, but the discovery of the Bajoran wormhole next to DS9 allowed easy access between the Alpha Quadrant (our bit) and the Gamma Quadrant (theirs). Suddenly, two factions who may otherwise never have met had each other in phaser lock.

The Changelings primarily exist in liquid form but can assume the form of multiple humanoid races. Despite possessing similar shapeshifting abilities to the Chameloid Martia in Star Trek 6: The Undiscovered Country, the species are apparently not related.

Odo in Deep Space Nine

Constable Odo spent the whole of Deep Space Nine learning about his Changeling origins. (Image credit: Paramount)

What is the Dominion?

The Dominion was the empire ruled over by the Changelings – known as the “Founders” to their adoring subjects.

Although the Founders were undoubtedly the brains of the operation, they were never particularly keen on getting their hands dirty. Instead, many administrative roles were fulfilled by the humanoid Vorta (easily cloned in the event of an individual’s demise). The Dominion’s military might, meanwhile, supplied by the ruthless Jem’Hadar. The Founders ensured the loyalty of their footsoldiers by genetically engineering them to be dependent on a drug known as ketracel-white.

What are the Changelings’ strengths and weaknesses?

Thanks to their morphogenic matrix, Changelings can shapeshift to impersonate a vast array of inanimate objects, animals and humanoids. As well having no need for food, they can survive in the vacuum of space.

On their homeworld they all join together to form a big lake of liquid beings known as the Great Link. Here they can exchange thoughts in one big hive mind – it’s like the Borg but gooier.

As predominantly liquid beings, however, they can’t hold solid form indefinitely. They subsequently experience intense pain and a rapidly deteriorating body if they leave it too long before returning to their liquid state. During Odo’s early days on Deep Space Nine, he had to revert to his gloopier self every 16-18 hours, spending his R&R periods in a bucket before relocating to larger quarters.

How do you spot a Changeling?

While Odo would struggle to pass for human, older, more experienced Changelings have the ability to create a seamless imitation of detailed facial features and voices. This has traditionally made them incredibly difficult to spot, with even the extensive blood screening adopted by the Federation proving frustratingly hit-and-miss. In fact, their best efforts weren’t enough to prevent copies of DS9’s resident doctor Julian Bashir and Klingon bigwig General Martok slipping through the net.

A Founder in Deep Space Nine

One of the Founders with her Jem'Hadar bodyguard. (Image credit: Paramount)

What was the Dominion War?

The Dominion’s initial slow-burn efforts to infiltrate the Alpha Quadrant eventually escalated into all-out war. The resulting two-year conflict brought all of Star Trek’s significant powers into battle, and led to in massive casualties on both sides.

Dominion tactics were varied enough to incorporate the brute force of the Jem’Hadar armada, and Changeling operatives shapeshifting their way into the upper echelons of Starfleet or the Klingon Empire – they even engineered a war between the Klingons and the Cardassians to further their aspirations in the region,  

The threat became so great that the Federation, the Klingon Empire and the Romulan Star Empire were forced to enter into an unlikely alliance, though the Cardassian Union went the other way and teamed up with the Dominion. This decision ultimately backfired when the Founders decided an alliance with the secretive Breen was actually more beneficial to their cause. Hundreds of millions of Cardassians were slaughtered in the subsequent invasion.

What happened to the Dominion at the end of Deep Space Nine?

The Federation/Klingon/Romulan alliance ultimately reclaimed Cardassian territory and gained the upper hand over the Dominion in battle. But arguably the most important (and most morally questionable) development of the war’s endgame was the morphogenic virus Starfleet Intelligence’s perennially shady Section 31 developed to kill off the Changelings.

With the Founders unable to develop a treatment of their own, they were facing extinction when the Federation Council vetoed the use of the cure Dr Bashir had developed.

Odo ultimately convinced the Founders to surrender, on the condition that he join them in the Great Link to share the cure. The war officially ended with the signing of the Treaty of Bajor.

Worf in Deep Space Nine

Worf has plenty of history with the Dominion (Image credit: Paramount)

Has Picard ever faced the Dominion before?

Neither of Picard’s Enterprises ever encountered the Dominion on screen, though the long-running war is referenced in both Star Trek: Insurrection and Star Trek: Nemesis. Seeing as the crew would have been in service throughout the conflict, however, it seems unlikely they’d have avoided the Changelings completely.

And, seeing as Worf spent four seasons as a regular on Deep Space Nine, there is at least one member of the classic Next Generation line-up with extensive experience of the Founders. When the Klingon makes a reference to “a close friend within the Link” in Picard season three’s third episode, he’s almost definitely referring to his former colleague, Odo.

How do the Changelings fit into Star Trek: Picard?

Episode 3 (‘Seventeen Seconds’) sets them up as season 3’s Big Bad, responsible for stealing both the troublesome portal weapon Vadic uses to torment the USS Titan, and another top-secret threat housed at Daystrom Station. There’s also a Changeling hidden aboard the Titan, and he's done his best to kill Jack Crusher in between ongoing efforts to sabotage the ship.

It’s important to note, however, that these Changelings are not the Dominion. Worf explains that, “When the Dominion War ended, there was a schism. A terrorist faction broke away, unwilling to accept defeat.” It appears that the Changelings we’ve seen so far in Star Trek: Picard are part of this “rogue group”, though Worf is treading softly because Starfleet realise that acknowledging their existence might risk reigniting the Dominion War.

New episodes of Star Trek: Picard stream on Paramount Plus in the US every Thursday, and on Fridays in the UK courtesy of Prime Video.

Richard is a freelancer journalist and editor, and was once a physicist. Rich is the former editor of SFX Magazine, but has since gone freelance, writing for websites and publications including GamesRadar+, SFX, Total Film, and more. He also co-hosts the podcast, Robby the Robot's Waiting, which is focused on sci-fi and fantasy.